The overall objective of this project is to develop a composite prosthesis that will be permanently incorporated by the host for use in segmental replacement of the esophagus or trachea. It will be designed using recent advances in the fabrication of a microporous lattice (Replamineform) with an elasticpolymer that can be reinforced with rigid rings and impregnated with a biodegradable material to provide a tight seal until bioincorporation occurs. The development of this experimental prothesis will be divided into two stages and will use the dog as an experimental model. The first stage will consist of short term evaluation of the healing characteristics of various moifications of the basic design. Specifications to be varied include type of polymer, micropore diameter and nature of biodegradable material. The second stage will be longer term studies of the healing and function of the most favorable design models. Obstructing lesions of the trachea and esophagus are often critical problems for which there are no simple, satisfactory protheses available for clinical use. We believe the propensity for host tissue ingrowth into a Replamineform microporous lattice an varied fabrication potential of the Replamineform process will allow the development of a prosthesis of greater promise than previous experimental replacements.